It is similar in a sense to Wine, how it is not a port of Wine. It is currently under development.
It is not an emulator in VMware/VirtualBox's sense of emulation. However it does implement small subset of Windows APIs, so it is a porting layer.
Apparently winulator just translates the windows api calls to the proper (native) android function, however why wouldn't you just port wine to android then? you'd probably just need to add a few missing posix functions, according to: http://mobilepearls.com/labs/native-android-api/STABLE-APIS....